Are 1000BASE-T and 100BASE-T compatible?

Question

Computer networks

Good day.
There is a stupid question about the compatibility of 1000BASE-T and 100BASE-T standards.
If there is a copper port whose specification says 1000BASE-T 802.3ab. And that's all, not a word about other standards ...
And there is another port, the old one, the 100Base-T standard.
Question: Will there be traffic between them?

Answer 1

Will, should agree on 100 mbit/s

Answer 2

Never met that links on an ezernet did not rise.